This invention relates generally to apparatus for weighing product and, more particularly, to a computerized scale for weighing product just prior to packaging of the product by an automatic packaging machine.
In general, a computerized scale of the foregoing type includes a series (e.g., ten) of so-called weighing buckets each associated with an underlying load cell or other means for producing an electrical signal representative of the weight of product in the bucket. Located above each weighing bucket is a holding bucket which contains a quantity of the product to be packaged. During each cycle, each empty weighing bucket is filled with product by momentarily opening the overlying holding bucket and allowing the product to fall into the weighing bucket. The weight of the product dropped into each weighing bucket is substantially less than the total weight of product which subsequently is placed in each package by the packaging machine.
After all of the weighing buckets have been filled, a computer responds to the weight signals produced by the different load cells, adds the weights in various combinations of weighing buckets and then selects the particular combination of buckets that meets the minimum statistical weight for the package to be filled while providing the least excess weight. The weighing buckets of that particular combination then are emptied and the product therein is delivered to the packaging machine to be deposited in the package.
The weighing bucket used in most conventional commercially available computer scales includes door means in the form of one or two hinged doors adapted to be opened to dump the product from the weighing bucket after the product has been weighed. After the product falls clear of the weighing bucket and the door means, the door means close and then the weighing bucket is re-filled by dumping an additional batch of product into the weighing bucket from the overlying holding bucket. Because the falling product must clear the weighing bucket and the door means before the door means can close, a computerized scale with ten conventional weighing buckets can not accurately cycle at rates much greater than sixty weighs per minute.